The field of the present invention resides in an electromechanical motor system in which the output applicator thereof is made to vibrate intermittently at an ultrasonic frequency, to produce bursts of ultrasonic mechanical vibrations repeated at a sonic frequency. The motor system thus produced is capable of producing effects characteristic of both ultrasonic and sonic vibratory devices.
Over the last decade a number of applications have been proposed and patented in which the introduction of ultrasonic mechanical vibrations has resulted in new and novel results. Towards this end the inventors of the present invention have pioneered in the development of ultrasonic motor-converter systems that could be manufactured and incorporated into home consumer products particularly where cost is a major consideration, as well as dental, medical, and industrial applications and uses. Towards this end the key consideration has been the development of a low cost converter-motor system that would permit the application of ultrasonic energy for use as in an ultrasonic home dental unit, ultrasonic shaving unit and ultrasonic hobby kit to name but a few. These and other uses are indicated in the referenced co-pending patent applications hereinafter referred to throughout the specification as the "applications" for convenience. A method and apparatus for the ultrasonic cleaning of teeth is disclosed in U.S. Pat. No. 3,375,820 which issued on Apr. 2,1968 to Arthur Kuris and Lewis Balamuth while an ultrasonic method and apparatus for shaving is disclosed in U.S. Pat. No. 3,610,080, which issued on Oct. 5, 1971 to Arthur Kuris. The entire subject matter of said Letters Patent are incorporated herein by reference as if fully set forth herein.
The present invention provides for the first time a motor-converter system with a minimum number of electronic components that enables the manufacture, in the low power range of, for example, from 1 to 10 watts, of instrumentation for home and other use which combines the beneficial effects of vibrations in the ultrasonic range, defined herein to include vibrations in the frequency range of 10,000 Hz to 1,000,000 Hz, and in the low sonic frequency range, defined herein to include vibrations in the frequency range at 10 Hz to 1,000 Hz.
The inventors have discovered that there are many instances where it is desirable to produce a mechanical vibration which in effect is a series of high frequency vibration bursts separated by predetermined time intervals, the separating time intervals being large compared with the time intervals for a period of the high frequency vibration. Such mechanical vibration is capable of producing all the necessary high frequency effect essential to ultrasonic motor technology. However, the pulsing effect imparts to the motors' applicator a kind of "jiggling" or "buzzing" effect during use. Among other advantages to this specific result of the double frequency system herein described is found in the fact that the buzzing action of the applicator during use gives the user the psychological assurance that the system is doing its job.
This signalling of the presence of the operating condition of the device has been found to be necessary in consumer devices such as hobby kits, razors, toothbrushes and the like using ultrasonic vibrations for producing their respective operative effects. In the prior art hand held ultrasonic devices, the user feels no difference in sensation in the hand holding the device when the device is "on" and when the device is "off". To be sure, visual aids may be used, such as a small pilot light, or an auxiliary sonic device to help the user know the device is on, but such aids add expense to the device which is unnecessary and is eliminated by the simplicity of the solution to this problem disclosed herein. Further, not only is the foregoing problem solved by the arrangement in accordance with the invention, but further desirable operative effects are produced in at least some of the ultrasonic devices in question.
Thus, the arrangement in accordance with the invention produces the completely unexpected results of a low frequency macro-massage type action, simultaneously with the ultrasonic micro-massage and other uniquely ultrasonic effects (due to cavitation, etc.) normally expected from the ultrasonic devices in question. One of the most important consequences of the invention is the establishment of a uniquely new method for applying ultrasonic energy to tissues with the synergistic benefit of simultaneous micro-massage and macro-massage.
A further unexpected beneficial result of the method and devices in accordance with the invention is the dramatic improvements in the application of ultrasonic energy for periodontal procedures, primarily for use in the home. Ordinary toothbrushing uses bristles and tooth paste to keep tooth surfaces clean and hopefully, polished and bright, a condition usually characterized as "whiten". In addition, an attempt is made to clean out interproximal, gingival crest, or gumline areas, and other hard-to-get-at areas without too much success. Conventional dental teaching requires the toothbrusher to learn how to stroke the gingival-tooth boundaries so as to provide some gum stimulation. Electric-vibratory, i.e., 60 cycle per second, toothbrushes attempt to meet all the above goals with greater efficiency and with the aid of outside electrical energy to provide additional motion to the bristles during use. However, such electric-vibratory toothbrushes merely utilize the principles of conventional toothbrushing. Recently, dental science has recognized the need for the removal of plaque during home periodontal care as an assist to the professional care ordinarily supplied by the dentist. However, conventional home cleaning devices used in a conventional manner fail to remove plaque.
The inventors have discovered that the addition of high frequency mechanical vibration energy to such elements as bristles or stimulents or other applicators permits the removal of plaque, thereby extending the benefit in oral hygiene normally obtained from the dentist to safe self-administered procedures followed by the patient at home. As is usual with high frequency mechanical vibration devices the benefits are multi-valued comprising the possibilities of micro-massage, fatigue destruction of calculus, interproximal cleaning due to cavitational energy in associated fluids being present, and the like.
The inventors have now found that the utilization of two frequencies in a vibratory system has produced unexpected beneficial effects, with each frequency performing its function such that the cummulative effect of the utilization of two frequencies exceeds the beneficial effect of either frequency working in its own frequency range. For example, with respect to the brushing or cleaning of teeth, it has been established that the high frequency energy is capable of moving plaque from the teeth with the low frequency introducing a macro-massage type action both on the gums and also cleaning teeth with respect to the effect that the low frequency range provides. Similar benefits are obtained in the field of shaving where the high frequency of vibratory energy plays its role as more particularly described in U.S. Pat. No. 3,610,080, and the low frequency component produces its own beneficial effect.
Aside from the ability for the first time to simultaneously utilize the beneficial results of two known frequency ranges in a single instrument, the arrangement and method in accordance with the invention produces results obtainable due to the combined effect of the two frequencies. Accordingly, the motor-converter system of the present invention may be utilized in such a manner that work may be performed on an object such that it may operate at an ultrasonic frequency and an audible frequency simultaneously with said ultrasonic vibrations. Since the current best ultrasonic motor art requires the vibration frequency of the motor to be at or near one of the natural vibration resonance frequencies of the motor, the current invention may use an automatic frequency control/feedback circuit which guarantees a selection of the desired aforementioned resonant mode.